Hard resins and thermoplastic elastomers have been molded into a multi-layers in the conventional art. This multi-layer molding makes use of the function of elastomers such as soft feeling and slip preventive property as a surface skin material, along with integrating the elastomer into a seal material and packing material to obtain a molded body with a good water-proof property. Integrated molding can also save the cost for adhering the hard resin with the thermoplastic resin. Many molded bodies and heat-fusion compositions have been recently proposed through the attempt to improve the fusion property of the hard resins and thermoplastic elastomers.
Japanese Examined Patent Publication No. 4-2412 proposes a multi-layer injection molded body comprising (a) an elastomer of a hydrogenated block copolymer obtained by hydrogenating a block copolymer comprising a polymer block A mainly composed of at least two vinyl aromatic compounds and a polymer block B mainly composed of at least one conjugated diene compound and (b) a resin selected from a polyolefin resin, polystyrene resin and ABS resin. However, the elastomer of hydrogenated block copolymers used in the invention cited herein has no functional groups to enhance the adhesive property, imposing a limitation in the heat-fusion property.
Japanese Unexamined Patent Publications No. 1-139240, No. 1-139241, No. 3-100045, No. 6-65467 and No. 6-107898 propose a method for producing a composite molded body comprising a thermoplastic elastomer composition, in which a styrene-based thermoplastic elastomer having no functional groups is combined with other thermoplastic elastomers, and a hard resin selected from polycarbonate, nylon 11, nylon 12, ABS resin and PMMA resin.
However, the styrene-based thermoplastic elastomers used in the invention cited herein has no functional groups to enhance the adhesive property, rendering the compositions poor adhesive property.
Japanese Unexamined Patent Publication No. 8-59954 proposes a composition in which (a) a hydrogenated block copolymer obtained by hydrogenating a block copolymer comprising a polymer block A mainly composed of at least. one vinyl aromatic compound and a polymer block B mainly composed of at least one conjugated diene compound, and/or a modified hydrogenated elastomer in which the hydrogenated block copolymer is bound with a molecular unit containing a carboxylic acid group or its derivative group, (b) a polystyrene based resin and/or a polyphenylene based polymer and (c) a thermoplastic elastomer comprising an ethylene--unsaturated carboxylic acid ester copolymer are laminated on a resin mainly composed of the resin (b). Although the heat-fusion property of the modified hydrogenated block copolymer as used herein has been improved by virtue of functional groups since the resin is modified with a carboxylic acid group or its derivative group, the resin is only able to fuse with so-called modified PPO resins. Accordingly, developments of a heat-fusion resin being able to fuse with an wider range of resins are desired.
The object of the present invention is to provide a heat-fusion composition that contains a block copolymer having epoxy groups and has a heat-fusion property with a hard resin, and a multi-layer molded body in which the layer comprising the heat-fusion composition and a layer comprising various kind of hard resins are strongly heat-fused.